Small diameter sausages such as frankfurters or the like usually are made using food casings of cellulose. Cellulose food casings or the like customarily are manufactured in long continuous tubular lengths. For handling convenience, these long tubular lengths are gathered into pleats by shirring and are longitudinally compressed by known techniques to obtain a shorter, relatively rigid tubular element known in the industry as a shirred casing stick. The coherency of a shirred stick is derived in part from the shirring operation which forms the casing into generally conical pleats which nest one within another.
During a stuffing operation the stick is loaded onto a stuffing horn and a food emulsion is fed through the horn and into casing which is drawn forward from the stick by the stuffing pressure. It is not uncommon for a shirred stick 50 cm long to contain upwards of 50 meters or more of casing so a large number of individual frankfurters are made with each stick.
Packaging and shipping of shirred sticks present several problems particularly for the type of casing used for frankfurters which generally have a wall thickness of only about 0.025 to about 0.05 mm.
For example, shirred sticks of this casing are relatively fragile in that the nested pleats of casing formed by the shirring operation are easily separated or pulled apart. If the pleats separate, the stick is said to break or lose "coherency". The result is one or more rigid shirred sections connected by loose unshirred sections. Sticks in this condition are not easily loaded onto a stuffing horn and are not at all suitable for automatic stuffing operations wherein the stick is loaded onto a stuffing horn by mechanical means. Accordingly, the packaging for the shirred sticks must be able to minimize stick breakage.
Shirred sticks also are susceptible to damage if made wet. Since stuffing machines frequently are hosed down with water after a stuffing operation, any sticks in the area must be retained in packaging which provides a barrier to water spray and is not itself damaged by water contact.
In commercial practice it generally is customary to package sticks in tight bundles of fifty (50) sticks. Bundling sticks together accomplishes several functions. For example, if the sticks are tight together, there is less likelihood of relative motion between the sticks so the sticks do not rub one against another. Rubbing together of sticks tends to produce undesirable pinhole damage in shirred casing. Also, a tight bundle helps to prevent bowing of individual sticks. Bowing is the result of a number of factors known in the art and is cause for concern because a bowed stick may not load onto a stuffing horn. A tight bundle further tends to reduce the likelihood of stick breakage as long as the bundle remains intact.
Conventional packaging for retaining a stick bundle generally is a carton or box made of corrugated fiberboard (cardboard) or a combination of corrugated fiberboard panels and a stretch or shrink wrap.
Shirred sticks are sold in a number of different diameters and lengths. While packages of fifty sticks are most common, counts of less than fifty sticks are usual for certain sizes of casings. Accordingly, different sizes of cartons and/or carton components must be kept in inventory to provide the appropriate packaging for a given number of each particular size (diameter and length) of stick. The need to obtain and stockpile carton or carton components in a variety of sizes adds to the packaging costs.
Moreover, there currently is a movement to reduce the amount of packaging materials used in order to alleviate the problems associated with collection, storage, disposable and possible recycling of the packaging materials after use. To this end, various alternative packaging arrangements have been proposed which eliminates the corrugated fiberboard components. Such alternatives simply bundle the shirred sticks together in various configurations using a flexible wrapper, stretch film, shrink film or the like. Typical packages of this sort are disclosed for example in U.S. Pat. Nos. 5,137,153; 5,228,572 and in pending U.S. application Ser. No. 08/030,923 filed Mar. 12, 1993 and Ser. No. 08/112,527 filed Aug. 27, 1993.
The use of a stretch or shrink film to bundle shirred strands of food casings reduces the volume of packaging materials and yet provides an inexpensive package which maintains the integrity of a bundle of shirred strands of food casings. Moreover, if the packaging film is in the form of a bag or the like, strands of shirred casing which are removed but unused, can be returned to the package for further storage.
One problem associated with packaging shirred strands of food casing in a stretch or shrink wrap is holding the strands in a stack configuration while wrapping a film around the stack. This drawback can be overcome by using premade bags and then supporting the bag so strands can be loaded into the bag. However, it is preferred for efficient operation to draw the packaging film from a continuous supply such as a roll.
Accordingly, one object of the present invention is to provide a method and apparatus for packaging shirred strands which utilizes a packaging film drawn from a continuous supply.
Another object is to form such a package by stretching a plastic film about a stack of shirred strands to bundle them together.
A further object is to provide a method and apparatus which utilizes a continuous tubular film for packaging a plurality of shirred strands of food casings.
In the method of the present invention, a film such as a heat sealable stretch or shrink film is drawn from a continuous supply. Preferably the film is tubular stock which is laid to its flat width and rolled up. An appropriate length of the film is drawn upwardly from a supply roll and opened. The strands of shirred food casing are stacked into the open tube. The open end of the tube is closed over the top of the stack and then the film is drawn tight and stretched about the stack. The film is clamped to hold it taught about the stack and then is heat sealed across its flat width to form a package which is severed from the film supply.
Drawing the film tight about the stack requires that the tubular film is closed over the top of the stack. This can be accomplished by folding the open end of tube over the top of the stack and applying a tape strip along the stack to hold the overlapped ends together. With this done, the film can be pulled downwardly to tension the film about the stack. Thereafter, the tubular film is heat sealed across its flat width along the bottom of the stack to form a tight bundle and then the bundle is severed from the film supply.
The package also can be formed from single plies of film rather than tube stock. This may be accomplished by drawing a like amount of film up over opposite sides of the stack from each of two film supplies, joining the two films over the top of the stack, pulling them downward to tighten them about the stack and then heat sealing the films together along the bottom of the stack.
Preferably, the film, either a flattened tubular film or two superimposed single sheets, is drawn vertically from the supply and supported so as to provide upstanding sides. The shirred strands then are laid downwardly into the space between these sides before the film is closed over the top of the stack.
As an alternative, film from two separate supplies are heat sealed across their flat width and are drawn upwardly from the supplies and formed to a tunnel shape structure. With this arrangement a stack of shirred strands can be inserted endwise into the tunnel shape. Thereafter, the films can be drawn downwardly to tighten them about the stack and a second heat seal made along the bottom of the stack.
Accordingly, the method of the present invention for packaging a plurality of shirred strands of food casings is characterized in one aspect thereof by the steps of:
a) arranging a supply of stretchable and a heat sealable film below a horizontal table; PA1 b) drawing superimposed sheets of said film from said supply and passing them upwardly through an elongated slot in said table until there is a sufficient length of film above the horizontal table to form a desired package; PA1 c) spreading said sheets to provide a space therebetween with portions of said film being draped along said table; PA1 d) loading strands of shirred food casings into said space and onto said table to form a stack comprising rows of said strands piled one on another; PA1 e) closing said sheets over said stack and pulling on said film from below said table to draw film downwardly through said slot and tension said sheets about said stack; PA1 f) clamping said sheets together across the film width at a location beneath said stack to maintain tension of the sheets about said stack; and PA1 g) heat sealing said sheets together below said clamping location and thereafter unclamping said sheets and severing said film supply below said heat seal to provide a tightly bundled stack of said shirred food casing strands. PA1 a) a horizontal table including means to receive and support a plurality of strands of shirred food casings arranged in a loose stack; PA1 b) a film supply disposed below said table and composed of two superimposed sheets of a stretchable and heat sealable film; PA1 c) said table having an elongated slot to accommodate passage of a length of said film upwardly through said slot for disposing said sheets over opposite sides of said stack; PA1 d) means below said table for gripping and pulling said film downwardly through said slot to draw said film tight about said stack; PA1 e) a clamp means closable across the width of said sheets for holding said film tight about said stack; and PA1 f) a heat sealer below said clamp means for heat sealing said sheets together across the flat width of said film.
The apparatus of the present invention may be characterized by